the role of desiccant in insulating glass vegas september 06 role... · 1 the role of desiccant in...
TRANSCRIPT
1
THE ROLE OF DESICCANT IN
INSULATING GLASS
THE ROLE OF DESICCANT IN
INSULATING GLASS
~ Davison
IGMA
Educational Seminar
Las Vegas, NV September 18 & 19, 2006
IGMA
Educational Seminar
Las Vegas, NV September 18 & 19, 2006
Presented by Steve Meisel Prepared by Dr Fritz Kilthau
TJ_Union Pres 2
Agenda
� The functions of desiccants in insulating glass
� Types of desiccants (MS, SG)� Selection of suitable desiccants� Correct handling of the desiccant during
insulating glass manufacture� Quality Control/questions to ask� DESICCANT in insulating glass - a review� DESICCANT MATRIX
TJ_Union Pres 3
Functions of the Desiccant in
Insulating Glass
� Wet air trapped in IG� Condensation at low
temperatures
Function #1:
Drying of the moisture trappedduring manufacture of the IG unit
TJ_Union Pres 4
PACKAGING “WEATHER”
Sealing an IG unit alone does NOT eliminate moisture, but rather
SEALS MOISTURE
Into the IG
TJ_Union Pres 5
� All sealants allow moisture to permeate through the barrier at some MVTR
� CBA Testing
- Uptake of the water vapor diffusingthrough the edge seal of the IG unit during its period of use
- Keep the trapped-in air / gas dry
Functions of the Desiccant in
Insulating Glass
Function #2:
TJ_Union Pres 6
� Sealants / Muntin bars / Glass cleaners / Corner pieces / Polymeric Spacers
� “Fogging”: Condensation of the off-gassed organics in the IG unit - Coated Glass
� Canadian Fog Test
- Uptake of organic vapors
Functions of the Desiccant in
Insulating Glass
Function #3:
TJ_Union Pres 7
Types of Desiccants: Silica Gel
� SiO2 structure� Highly porous� Non-uniform pore sizes:
Ranging from 20 to 200 Ångstroms
REM photograph of a Silica Gel in 15000X magnification
TJ_Union Pres 8
Types of Desiccants:
Zeolites (Molecular Sieves)
� Crystalline � Highly porous crystals � Uniform pore sizes:
3 Ångström (3 x 10-10 m)
10 Ångström(10 x 10-10 m)
REM photograph of a 3Å-MS in 15000X magnification
TJ_Union Pres 9
� Dependent on the gases/vapors in the insulating glass:� Water vapor ���� should be adsorbed� Air (nitrogen/oxygen) ���� should NOT
adsorbed� Argon/Xenon ���� should NOT be adsorbed� Solvents/Plasticizers � should be adsorbed
Selection of Suitable Desiccants
TJ_Union Pres 10
Selection of Suitable Desiccants:
Cause of IG Unit Deflection
� Temperature variation� Atmospheric pressure variation� Difference in height between
manufacture and installation� Adsorption of the trapped moisture� Adsorption of air (nitrogen/oxygen) or
Argon/Xenon pin< pout pin= pout pin> pout
TJ_Union Pres 11
Selection of Suitable Desiccants:
Impact of IG Unit Deflection
� Distortion of reflection image� Reduced thermal conductivity - comfort and
energy � Increased stress of the edge seal, faster aging,
higher water vapor transmission rate, reduced IGU life-times
� Danger of glass breakage - particularly smaller units pin< pout pin= pout pin> pout
TJ_Union Pres 13
Selection of Suitable Desiccants
Adsorption Properties In IGU Conditions
H2O N2 O2 Solvents
3A yes no no no
4A yes yes yes no
10A yes yes yes yes
Silica Gel no no no yes
TJ_Union Pres 15
Correct Handling of the Desiccant
During IG Manufacture
Storage� Under roof� Dry� Bag/Super Sack: no exposure to UV radiation� Storage time (on packaging: date of
manufacture)Drum: max. 4 years
Bag: max. 1 year
Bag-in-Box: max. 1 year
Super Sack: max. 0.5 years
TJ_Union Pres 16
Square Wave Diffusion Model
Driver: High affinity of zeolite for water
time
humidity
time
humidity
active zeolite particle
water saturated zeolite particle
Open Drum/Bag time
Correct Handling of the Desiccant
Water Absorption Capacity
TJ_Union Pres 17
Delta-T Test
Principle:� Active MS in water:� Heat released � leads to a
temperature rise (Delta-T)� Delta-T test is an easy, but
rough test to check on the activity of the desiccant
Control of the Activity
of the Desiccant Before Use
TJ_Union Pres 18
Supply drum at LISEC filling machineIn the case where the supply drum is filled from bags, the drum should be cleaned from time to time!
Correct Handling of the Desiccant
During IG Manufacture
Prevention of dust!
TJ_Union Pres 19
Desiccant Recommendation Based on
Sealant Configuration
� Hot Melt Butyl 3A or SiO2 Blend� Polyurethane 3A or SiO2 Blend� Polysulfide SiO2 Blend� PIB/PU 3A or SiO2 Blend� PIB/PS SiO2 Blend or 3A� PIB/Silicone SiO2 Blend or 3A
TJ_Union Pres 21
Influencing Parameters:� Perforation of the spacer bar� Number of filled profile sides� Spacer Size� Desiccant type� Gas filling� Temperature at Manufacture� Relative Humidity at Manufacture
Hang Time Studies
TJ_Union Pres 22
Supplier Quality Control
� Adsorption Capacity� Gas Desorption� Dust� Particle Size� Packaging� Technical Support - Lifetime estimations,
trouble shooting, hang time studies…..� Shipping
TJ_Union Pres 23
Questions to Ask When
Comparing Desiccants
� At what relative humidity and temperature is water capacity measured?
� When comparing desiccants what is the density? - manufacturers filling by volume
� Size vs. spacer opening - Will it fill correctly?� Is material low deflection?� ISO 9000
TJ_Union Pres 24
Properties of a Desiccated Matrix
� Adsorb Moisture.� No off-gassing.� No adsorption of Argon, Nitrogen,
Oxygen.� Adhesion to the U-channel spacer.� Pumpability.� Spreadability - Aesthetics.� UV Stable.
TJ_Union Pres 25
spacer bar
Primary Seal
Lite
desiccant
Secondary SealantLite spacer
polymer withdesiccantPrimary Sealant
Secondary Sealant
ConventionalInsulating Glass
Intercept®
Loose Fill or Matrix
TJ_Union Pres 26
Functionality
1. Drying the unit down initially after manufacture.
• Typically only requires less than 0.5g of desiccant.
• Units dry down to -90ºF in 18 hours.
2. Adsorbing moisture that permeates through the sealant over the lifetime of the insulted glass unit.
• Dependent on MVTR of sealants, sealant application and manufacturing.
3. Adsorbing off gassed organics from desiccated matrix, sealants, mantis…
TJ_Union Pres 27
Types of Desiccant Matrix Materials
Hot Applied SystemsRequires Hot Melt pump.
Long shelf life.No Cure times - Adhesion properties are constant
Cold Applied SystemsDoes Not require Hot Melt pump.
Liquid material - Chemically cures - Adhesion properties improve with curing.Shorter shelf life.
Warm Applied SystemsHybrids of the Above
TJ_Union Pres 28
Types of Desiccant Matrix Materials
HOT APPLIED (Over 200ºF) ADCOBostik
Grace DavisonH.B. Fuller
WARM APPLIED (~ 160 ºF)Bostik
H.B. Fuller
AMBIENT APPLIED (Room Temperature)PRC Desota
TJ_Union Pres 29
Application Rates
� How Much do I use?� Questions to ask yourself -
� How Long do I want my IGU to last?� What is the MVTR of my sealant?� Is that MVTR result relevant to my sealant
application?� Have I taken into account manufacturing,
deflection…..
TJ_Union Pres 30
Application RatesOnce questions have been answered
� Calculation - Assumes perfect manufacturing, no elongation of sealant due to deflection.
� CBA testing - Really a sealant test� Comparison to historical data/loadings
TJ_Union Pres 31
Application Rates
Equivalent loading of rectangular spacer Allmetal 1/2” std spacer. Typical IGU size 3x5 foot with 2 side fill rate 16.6g/ft estimate of 75% sieve.
� 16.6g x 0.75 x 8ft = 99.6 grams of desiccant in a traditional unit
Equivalent loading of Desiccant Matrix with 57% sieve with 6.1g/ft four side filling.
� 6.1g x 0.57 x 16ft = 55.6grams of desiccant
Equivalent Loading of same unit with a desiccant matrix having 50% sieve and a 4 gram recommendation
� 4g x 0.5 x 16ft = 32 grams of desiccant
TJ_Union Pres 32
Application Rates
IGMA FIELD CORRELATION STUDIES
10 Year Data: Class CBA 2.5% failures
15 year Data: Class CBA 4.3% failures
TJ_Union Pres 33
Quality Controls
Supplier Checks -Adsorption Capacity
Adhesion Slump Testing
Melt IndexViscosityGrit Test
UV Testing - Stability and Offgassing
TJ_Union Pres 34
Quality Controls
Manufacturers Controls/ChecksNo activity test like loose fill
(EXCEPTION PRC)
Application Rate - Measure on routine Basis(Equipment now available to lay down to the .1g)
Clean spacer
Hang times No more than Four hours
TJ_Union Pres 35
Conclusions
� Desiccants have three functions –
1)Adsorbing the moisture included during the manufacture of the IGU
2) Second most important is to adsorb any off-gassed organics WITHOUT causing deflection
3) Adsorb moisture that permeates through the seal
� There are three commercially applicable desiccants available
1) 3Å
2) 3Å/10 Å Blend
3) 3Å/Silica Blend
TJ_Union Pres 36
Conclusions
� When you purchase desiccant matrix you are purchasing adsorption capacity - Ask your supplier how much desiccant is included. Then ask your supplier’s competition
� Different types of adsorbent used in desiccant matrix materials.
� No Real Easy Test - Ask for Certificate of Analysis.
� How Long do you want your IGU to last -reinvestigate your application rate.